Stock TPI Throttle-bodies have dual 48mm openings and are able to be ported out to 52mm and replacing valves. 58mm TBs are new units.

Flow and HP ratings for Throttle-bodies:
                               Flow (cfm)           Approx. Max NA HP
Stock                           668                           300
Stock w/airfoil          710                           350
52mm w/airfoil         835                           400
54mm (AS&M)       900                           450
58mm                       1050                           500

Click on any image below for an enlargement (~500K) image.



Stock TB, measured front diameter "flared out" (51mm)


Stock TB, measured front diameter "flaired out" (51mm)


Stock TB, measured rear diameter lip (49mm)


Stock TB, measured rear diameter chamber (48mm)


Edelbrock TB (pn 3804), measured front diameter "flared out" (58mm)


Edelbrock TB, measured front diameter "flared out" (58mm)


Edelbrock TB, measured rear diameter (58mm)


Edelbrock TB, fullview with stock TPS and top cover plate installed


Edelbrock TB, fullview with stock IAC housing installed


Edelbrock TB, View thru into ported plenum


Edelbrock TB, View thru into ported plenum


Here are some pictures of the 2 Edelbrock/BBK 58mm twin throttlebodies I received, one ordered, the second arriving as a replacement for the "damaged" first one.. I was expecting a nice smooth "hour glass" flow shape in between the bores, ("cast in flow improver") but instead I get two that look like a "broken nose", flattened and far from a smooth flow.

Am I being picky, or should the product look like the picture on the box?



First product I received, compared to box picture


First product I received, closeup


Second product I received, compared to box picture


Second product I received, closeup


Box picture closeup